That's exactly how I got Windows ME. What other OSs and Utilities did MS put on those CDs? Are there any places to buy/download the full set of CDs.
Pretty much everything, starting with DOS 6.0, IIRC. DOS, Win9x (including service upgrades), NT 3.1, 3.51, 4.0 (in different platform versions), 2K, XP (also in server versions). All in just about every language that MS supports. Beta versions and release candiates out the wazoo.
Buy a complete set? Maybe if you shell out for an MSDN subscription, but maybe not, since MS doesn't appear to keep old OSes around. At any rate, it'd run you a substantial pile of lucre, I'll wager. At first, MSDN looked like MS was probably breaking even on the deal, then the subscription rates got considerably more expensive. I think it's a profit center for them now.
MSDN OSes either had their own keys or the keys were preset in the product itself.
I dropped out of the program sometime after XP, but before Vista since it was cheaper to just buy the OS I needed and I didn't need the bucketload of CDs and DVDs that I'd never use.
MSDN served a purpose when communications were slow, since the bandwidth of a bunch of CDs arriving by UPS was probably greater than anything you could get from your local internet provider. But no more.